What player are you using? Sounds like you need to d/load some codecs or try another player.

Try using VLC media player, it has the codecs built in and will play most file types. It's a good player to keep around for those stubborn files that you can't get to play.

For WMP, K-Litecode Codec Pack gets recommended a lot. I use XP Codec Pack 2.0.6 and rarely have any trouble playing a file.

If your OS is Vista try: Vista Codec Package v4.4.8 (freeware).

CODECs list & alternate players for Videos and Audio

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